Superfeed system for two-stroke internal-combustion engines



Feb. 28, 1928. 1,660,610

G. FoRNAcA SUPERFEED SYSTEM FOR Two-STROKE TcNTERNAL COMBUSTION ENGINES Filed Jan, 14- 1927 Patented Feb. 28, 1928.

y1,660,610y I PATENT OFFICE.

GUIDO FOBNACA, F TURIN, ITALY.

SUPERFEED SYSTEM FOR TWO-STROKE INTERNAL-COMBUSTION ENGINES.

Application led January 14,1927, Serial No. 161,215, and in Italy January 20, 1926.

The two stroke engi-nes of the kind that are super-fed by means of a compressor arranged between the Carburettor and the cylinders showv theY great inconvenience that when changing suddenly from high to low speed, an instantaneous fall 0f pressure takes place between the Carburettor yvalve and the compressor and` consequently, between the compressor and` the cylinders. rlhis causes dangerous back firing in tliefeed tubes or l conduits. A f n Said inconvenience, which takes'place especially. in engines in which the closure of the inlet ports is retarded with respect to the exhaust poi-ts, is fully rcinoved'by the arrangement according to the present 1nveiition, which is substantially characterized by the interpostion of an automatic vValve between the usual Carburettor valvel and the` compressor.

The automatic valve isso adjusted that if the Carburettor valye is quickly closed while the engine is still running at the highest speed, it will open, owing to the exceptional fall of pressure produced, to admit air into the conduit, thus re-establishing at the inlet y Aports the lowest pressure necessary to lprevent back tiring. As the engine `.speed decreases, the automatic valve will close and the engine will continue'to workfat a lowery speed.

The annexed drawing shows, by "wayrof,l

example,- a diagriirrimatic form of construction of the arrangement applied to a two y stroke engine of the opposed piston type.I

crank shafts 3, 8 that are connected, by means of rods 4, 4 with the pistons 5, 5.

The cylinders 1 are provided with exhaust ports 6 and with inlet ports 7. The inlet ports are fed through the tube 8 from a conipressor 9 that draws the mixture from the' fore the butterfly valve 12 is suddenly closed, ,i

a strong `tall of pressure will take place in the conduit 1l and the feed pressure in the tube 8 `will be greatly decreased. This fall 'of pressure in the conduit l1 causes the valve- 13 toropeii and the air thus admitted brings the pressure to asuitable value, thus avoiding buck firing. Meanwhile, the speed of the engine is rapidly lowered, the compressor draws a smaller amount of mixture so that the valve 13 closes, and the feed is .effected at the ordinary reduced rate.

What I claim is:

In a\twostroke internal combustion engine the combination of an engine cylinder, a'v

compressor communicating therewith, a carburettor, a conduit connecting the latter with the compressor, a manually operated fuel control valve in the conduit, and a Valve V opening into the latter between the compressoi and said control valve operable automatically by a fall ofl pressure in the conduit `upon the sudden closing of the control valve,

thereby admitting air for preventing back ring.

my invention, I have si 'ed my name.

G O FORNACA.

In testimony that I claim the foregoing as 

